From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org Received: from alsa0.perex.cz (alsa0.perex.cz [77.48.224.243]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.lore.kernel.org (Postfix) with ESMTPS id BCB1CC7EE39 for ; Sun, 29 Jun 2025 15:16:01 +0000 (UTC) Received: from alsa1.perex.cz (alsa1.perex.cz [45.14.194.44]) (using TLSv1.3 with cipher TLS_AES_256_GCM_SHA384 (256/256 bits) key-exchange X25519 server-signature RSA-PSS (4096 bits) server-digest SHA256) (No client certificate requested) by alsa0.perex.cz (Postfix) with ESMTPS id 1404E601EC; Sun, 29 Jun 2025 17:15:48 +0200 (CEST) DKIM-Filter: OpenDKIM Filter v2.11.0 alsa0.perex.cz 1404E601EC DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=alsa-project.org; s=default; t=1751210158; bh=G02GPmpiAQkZ4YnHIk/5bHsJpLLAMC1+Rkh4rOhd9sE=; h=From:To:In-Reply-To:References:Subject:Date:List-Id:List-Archive: List-Help:List-Owner:List-Post:List-Subscribe:List-Unsubscribe: From; b=UWQRIyHyCvLSwgpIUBmefWZGqlx8SZD8A2BR/98XZmuW8XVNFc9FDGCUqvUjBfcB4 hC/F1MC7BDsAKaeejxWDn/N3fAkS7pz9rr3ys/Z/b/8ILcSGOJMMiQ830aIoyv7F/+ QcZ80cq7SdSbQfG/z+whOSn0uFCKkutR+XYIen00= Received: by alsa1.perex.cz (Postfix, from userid 50401) id 8307CF805D5; Sun, 29 Jun 2025 17:15:20 +0200 (CEST) Received: from mailman-core.alsa-project.org (mailman-core.alsa-project.org [10.254.200.10]) by alsa1.perex.cz (Postfix) with ESMTP id 0DE36F805BD; Sun, 29 Jun 2025 17:15:20 +0200 (CEST) Received: by alsa1.perex.cz (Postfix, from userid 50401) id 67843F80254; Sun, 29 Jun 2025 17:15:17 +0200 (CEST) Received: from webhooks-bot.alsa-project.org (vmi2259423.contaboserver.net [45.14.194.44]) by alsa1.perex.cz (Postfix) with ESMTP id C3497F800B5 for ; Sun, 29 Jun 2025 17:15:15 +0200 (CEST) DKIM-Filter: OpenDKIM Filter v2.11.0 alsa1.perex.cz C3497F800B5 MIME-Version: 1.0 Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit From: GitHub issues - opened To: alsa-devel@alsa-project.org Message-Id: <184d8c52550dd700-webhooks-bot@alsa-project.org> In-Reply-To: <184d8c5255085f00-webhooks-bot@alsa-project.org> References: <184d8c5255085f00-webhooks-bot@alsa-project.org> Subject: Focusrite Scarlett 18i20 Gen 1: UCM configuration defines incorrect capture channel count Date: Sun, 29 Jun 2025 17:15:17 +0200 (CEST) Message-ID-Hash: A73LNQJ4WDFHU4ESRPQRICUHP7F6YKCS X-Message-ID-Hash: A73LNQJ4WDFHU4ESRPQRICUHP7F6YKCS X-MailFrom: github@alsa-project.org X-Mailman-Rule-Misses: dmarc-mitigation; no-senders; approved; emergency; loop; banned-address; member-moderation; header-match-alsa-devel.alsa-project.org-0; header-match-alsa-devel.alsa-project.org-1; nonmember-moderation; administrivia; implicit-dest; max-recipients; max-size; news-moderation; no-subject; digests; suspicious-header X-Mailman-Version: 3.3.9 Precedence: list List-Id: "Alsa-devel mailing list for ALSA developers - http://www.alsa-project.org" Archived-At: List-Archive: List-Help: List-Owner: List-Post: List-Subscribe: List-Unsubscribe: alsa-project/alsa-ucm-conf issue #588 was opened from mkuhl: ## Summary The ALSA UCM configuration for Focusrite Scarlett 18i20 incorrectly defines 20 capture channels (`Define.DirectCaptureChannels 20`), but the 1st generation hardware only supports 18 channels. This causes the device to fail initialization with UCM profile errors. ## Device Information - **Device**: Focusrite Scarlett 18i20 (1st Generation) - **USB ID**: 1235:800c - **USB Name**: Focusrite Scarlett 18i20 USB - **Driver**: snd_usb_audio ## Channel Configuration (Gen 1) - 8 analog inputs - 8 ADAT inputs - 2 S/PDIF inputs - **Total**: 18 input channels (not 20) ## Error Message ``` spa.alsa: Error in ALSA UCM profile for _ucm0007.hw:USB,0 (HiFi: Direct 2: source): CaptureChannels=20 > avail 18 spa.alsa: Errors in ALSA UCM profile for card Scarlett 18i20 ``` ## Affected Files The channel definition is in the main configuration file: `/usr/share/alsa/ucm2/USB-Audio/Focusrite/Scarlett-18i20.conf` Current (incorrect): ``` Define.DirectCaptureChannels 20 ``` Should be: ``` Define.DirectCaptureChannels 18 ``` This file then includes `Scarlett-18i20-HiFi.conf` which uses the defined value. ## System Information - **Distribution**: Fedora 42 / Aurora-dx - **Kernel**: 6.15.3-200.fc42.x86_64 - **PipeWire**: 1.4.5-1.fc42 - **WirePlumber**: 0.5.8-1.fc42 - **ALSA UCM**: 1.2.14-2.fc42 - **ALSA lib**: 1.2.14-2.fc42 ## Steps to Reproduce 1. Connect Focusrite Scarlett 18i20 Gen 1 (USB ID 1235:800c) 2. Start PipeWire/WirePlumber 3. Check device status: `wpctl status | grep Scarlett` 4. Device shows "[ALSA UCM error]" 5. Journal shows channel count mismatch error ## Workaround Users can create a local override: ```bash mkdir -p ~/.local/share/alsa/ucm2/USB-Audio/Focusrite/ cp /usr/share/alsa/ucm2/USB-Audio/Focusrite/Scarlett-18i20.conf \ ~/.local/share/alsa/ucm2/USB-Audio/Focusrite/ cp /usr/share/alsa/ucm2/USB-Audio/Focusrite/Scarlett-18i20-HiFi.conf \ ~/.local/share/alsa/ucm2/USB-Audio/Focusrite/ sed -i 's/Define.DirectCaptureChannels 20/Define.DirectCaptureChannels 18/g' \ ~/.local/share/alsa/ucm2/USB-Audio/Focusrite/Scarlett-18i20.conf ``` ## Root Cause Analysis The UCM configuration appears to be written for newer Scarlett 18i20 generations (2nd/3rd/4th Gen) which may have 20 channels due to additional loopback channels. The configuration includes generation detection logic but doesn't properly identify USB ID 1235:800c as a 1st Gen device, causing it to use the default 20-channel configuration. ## Proposed Solution The UCM configuration should detect Gen 1 devices and set the appropriate channel count: 1. Add detection for USB ID 1235:800c as Gen 1 2. Set `DirectCaptureChannels` to 18 for Gen 1 devices 3. Keep 20 channels for newer generations if applicable ## Impact - Device fails to initialize properly - Users cannot use the audio interface without manual workarounds - Affects all Linux distributions using this UCM configuration ## Additional Information - This is a regression - older ALSA versions worked correctly - The issue affects PipeWire/WirePlumber but not JACK when using Pro Audio profile (which bypasses UCM) - Other Gen 1 Scarlett devices (6i6, 8i8) may have similar issues ## References - Device specifications: https://support.focusrite.com/hc/en-gb/articles/206849839-Scarlett-1st-Gen-Tech-Specs Issue URL : https://github.com/alsa-project/alsa-ucm-conf/issues/588 Repository URL: https://github.com/alsa-project/alsa-ucm-conf